No doubt, but it is over a month since they were approved and seems use in service is not imminent. As weeks turn to months speculation that there are real problems still to sort out is inevitable.
I think that's a completely normal timescale for new rolling stock. I haven't read anything that suggests a major issue with the Stadler fleet.
Clearly it's going to be a while with much of the delivered fleet currently in storage. I guess the focus is on getting the initial fault free running required on one example of each type, and then commence mileage accumulation on the rest.
There's probably little point trying to do those two things concurrently, even if the resources to do it existed. For example, if a software issue is found with the initial units then the fix would need to be applied to them all.
It makes more sense to shake out any common issues on as few units as possible, apply the fixes across the fleet and then test individual units to find their individual faults.
Any other approach would result in chaos.
And there's still all of the drivers, guards, catering and platform staff to train.
It all takes time and can't be done overnight.